Screen Tearing
Screen tearing is a frame rendering phenomenon that creates a jarring user experience. Screen tearing is different from screen stuttering, and the two phrases cannot be interchanged; that said, the two are related in that they often occur in opposition. “Screen tearing” specifically refers to an instance where the GPU has begun drawing the next frame while the current frame is still displayed, resulting in a horizontal shear in the visual output between the old and new frames. A screenshot is provided below for example.
Why does Screen Tearing happen?
A 60Hz monitor is refreshing itself every 16 milliseconds, and so in a perfect world, it should receive a new frame from the GPU exactly on (or just before, stored in the framebuffer) that 16ms mark. 120Hz and 144Hz displays are even more demanding at 8ms and 6.9ms, respectively.
In the real world, a GPU will exhibit inconsistencies when rendering frames – some scenes are more complex than others, and thus get drawn at variable rates. With V-Sync disabled, the GPU will draw a frame to the display immediately when that frame is ready to begin output. To this end, the frame output is somewhat haphazard and means that frames are being drawn in the middle of the old frame, creating a horizontal tear when the old frame meets the new frame.
This is where adaptive refresh rate technologies like G-Sync and FreeSync come in, but each is out of the scope for this definition (see below links).
Screen tearing can be eliminated by enabling V-Sync, but this introduces Stuttering (GPU). Competitive gamers may find tearing preferable to stuttering, part of why it is generally recommended to disable V-Sync and just live with the torn frames.
Purchasing a G-Sync display or FreeSync display can resolve both stuttering and tearing.
See Also
- Stuttering (GPU)
- V-Sync
- FreeSync
- G-Sync
Read More
- AMD FreeSync is Here: How it Works.
- How nVidia G-Sync Works.
- Another Recap of Adaptive Sync Technology.
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